In Japanese Patent Application Laid-Open (KOKAI) Nos. 1-93574 (=U.S. Pat. No. 4,938,792) and 1-301664 (=European Patent No. 0329397), there is described 5-[(4-chlorophenyl)methyl]-2,2-dimethylcyclopentanone and 5-[(4-chlorophenyl)methyl]-2,2-dimethyl-1-(1H-1,2,4-triazol-1-yl methyl)cyclopentanol (Metconazole) is derived therefrom by converting the carbonyl group thereof into an epoxy group and then introducing an azolyl group into the epoxidated product. In Japanese Patent Application Laid-Open (KOKAI) No. 1-93574 (=U.S. Pat. No. 4,938,792), as a process for producing 5-[(4-chlorophenyl)methyl]-2,2-dimethylcyclopentanone, a method represented by the following reaction formula (I) is described.

However, in the reaction formula (I), the yield of the compound (2) in the reaction of from the compound (1) to the compound (2) is 81%, the yield of the compound (3) in the reaction of from the compound (2) to the compound (3) is 86%, and, therefore, the total yield of the compound (3) in the reaction of from the compound (1) to the compound (3) is as low as 70%.
Also, in Japanese Patent Application Laid-Open (KOKAI) No. 8-245517 (=U.S. Pat. No. 5,681,979), there is described a method of reacting 1-[(4-chlorophenyl) methyl]-3-methyl-2-oxocyclopentanecarboxylic acid methyl ester with sodium hydroxide and methyl bromide in the presence of molecular sieves to obtain 5-[(4-chlorophenyl) methyl]-2,2-dimethylcyclopentanone as represented by the following reaction formula (II):

However, in the reaction formula (II), the yield of the compound of the reaction of from the compound (4) to the compound (2) is also as low as 71%.
In the reaction formula (II), when R is isopropyl, the yield is increased to 90% as described. However, since the obtained product (2) [R=isopropyl] has a high resistance to hydrolysis in the subsequent step, the compound (2) is not suitable as a raw material for 5-[(4-chlorophenyl)methyl]-2,2-dimethylcyclopentanone.
Further, in Japanese Patent Application Laid-Open (KOKAI) No. 1-93574 (=U.S. Pat. No. 4,938,792), there is described a method of the production of the above compound (4) in the reaction formula (II), as represented by the following reaction formula (III). However, there is no description about the yield of the compound (4).

As a method of the production of the compound (5), there is also known the method represented by the following reaction formula (IV), as described in “Precision Organic Synthesis” (published by Nanko-Do Co., Ltd.). However, any of these methods fails to achieve a high yield of the aimed product.

Thus, there is unknown a method of producing 5-[(4-chlorophenyl)methyl]-2,2-dimethylcyclopentanone from dimethyl adipate or diethyl adipate which are industrially readily available, at a high yield. Therefore, it has been required to develop a process for effectively producing the above compound.